The invention relates to the lighting arts. It is especially applicable to the packaging of light emitting diodes (LED""s) to form a spot light, flashlight, or other lamp type, and will be described with particular reference thereto. However, the invention will also find application in packaging of LED""s, semiconductor lasers, halogen bulbs, and other light emitting elements for lighting and other optical applications.
Lighting systems are advantageously flexible in terms of the light output spatial pattern or angular distribution. Flashlights, work lights, spot lights, and other lighting systems preferably can emit light at different angular distributions, e.g. narrowthrough wide-beam. A desk lamp preferably is adjustable to light only the present work area thereby most efficiently using the light generated by the lamp. In the desk lamp case, the work area is often rectangular, and so the spatial pattern of the emitted light is preferably arranged to fill the rectangular work area at the desk surface.
The prior art includes limited control over the angular distribution of the light emitted by light sources such as incandescent light bulbs, halogen lamps, and light emitting diode-based light sources. Flashlights which have variable beam expanding optics are known. However, such flashlights typically provide only a single level of control, e.g. narrow circular beam versus wider circular beam. Halogen bulbs typically come with fixed prescriptions, e.g. the MR16 halogen bulb series that provides narrow angle, wide angle, and medium angle flood characteristics. In order to change the spatial characteristics of the light output in a lamp using such a fixed-prescription halogen bulb, it is usually necessary to physically replace the bulb.
In the above-cited prior art, the adjustment is limited to isotropic, i.e. circular adjustment of the angular distribution of the light beam. Desk lamps are also known that have rectangular reflector hoods, usually used in conjunction with tubular fluorescent lamps, that emit light with a non-circular distribution. However, the spatial distribution of the light output of such lamps is usually not adjustable.
The present invention contemplates an improved light source or lamp that overcomes the above-mentioned limitations and others.
In accordance with one embodiment of the present invention, a lamp is disclosed, that includes a substrate. A first lighting unit includes a first light emitting diode (LED) arranged on the substrate and a first lens element having a first optical prescription and being arranged to interact with light produced by the first LED. A second lighting unit includes a second light emitting diode (LED) arranged on the substrate and a second lens element having a second optical prescription and being arranged to interact with light produced by the second LED.
In accordance with another aspect of the present invention, a control unit applies operating power to at least one of the first lighting unit and the second lighting unit.
In accordance with another aspect of the present invention, a control unit has at least two selectable operational modes. A first selectable operational mode applies power to the first lighting unit. A second selectable operational mode applies power to the second lighting unit. Optionally, a third selectable operational mode applies power to both the first lighting unit and to the second lighting unit.
In accordance with another aspect of the present invention, the light emission from the first LED has a first spectral distribution, and the light emission from the second LED has a second spectral distribution that is different from the first spectral distribution.
In accordance with another aspect of the present invention, at least one of the first lens element and the second lens element includes a tinted region whereby the spectral distribution of the light emission of the at least one lighting unit that includes the tinted region is altered in a pre-selected manner by the tinted region.
In accordance with another embodiment of the present invention, a light source having a selectable light output is disclosed. A plurality of optical sources are arranged on a substrate. Each optical source includes a light emitting diode and an optical element in operative communication with the light emitting diode and having a pre-defined optical prescription. The plurality of optical sources are selectively operable to produce light having selected light output characteristics.
In accordance with another aspect of the present invention, the selective operation of the plurality of optical sources includes at least one of: selectively operating one of the plurality of optical sources; selectively operating a sub-set of the plurality of optical sources; and selectively operating all of the plurality of optical sources.
In accordance with another aspect of the present invention, the selected light output characteristics include selected spatial light output patterns.
In accordance with another aspect of the present invention, the selected light output characteristics include selected angular distributions of the emitted light. Optionally, the selected light output characteristics also include selected light colors.
In accordance with another aspect of the present invention, a control unit operates selected optical sources producing a spatial and angular distribution of the light source output. The control unit optionally also includes electrical circuitry that conditions the power applied to at least one of the first optical source and the second optical source
In accordance with another aspect of the present invention, the optical element includes a first lens element formed according to the pre-defined optical prescription.
In accordance with yet another aspect of the present invention, in an LED light source comprising a plurality of light emitting diodes disposed on a substrate each in optical communication with a lens, a method of varying light patterns produced by the LED light source is disclosed. A first set of the plurality of light emitting diodes is selected. Light emitting diodes in the first set of light emitting diodes are powered. Light emitted by each of the powered light emitting diodes in the first set passes through lenses integral with each of the powered light emitting diodes in the first set producing a first angular distribution of light. A second set of the plurality of light emitting diodes is selected. Light emitting diodes in the second set of light emitting diodes are powered. Light emitted by each of the powered light emitting diodes in the second set passes through lenses integral with each of the powered light emitting diodes in the second set producing a different angular distribution of light.
In accordance with another aspect of the present invention, the method further includes depowering at least selected light emitting diodes in the first set prior to powering the light emitting diodes in the second set.
In accordance with another aspect of the present invention, the method further includes altering a wavelength associated with the different angular distribution of light such that the different angular distribution of light comprises a color different than the first angular distribution of light.
Numerous advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.